Tag Archives: transect 7

1 o’clock, 2 o’clock, 3 o’clock rock (well…compressed mud), you can rock around the clock….

By Margot Saher and Lou Callard

Take some of the ‘finest’ brains in the country. Put them on a state-of-the-art research vessel which is filled to the brim with geophysical equipment, and has its own core scanning lab. Imagine what one could do with that! And what do we do with it? What is the scientific treasure we hunt? Mud. Six weeks at sea for mud (occasionally sand…)? We’ll be scrutinising it for years to come! Without mud the whole endeavour would be a failure; the mud must be treasured, cared for. It is the sedimentary archive that could answer the question of when and how the British-Irish Ice Sheet vanished. It is the wet lab coring teams that handle, care for and love the mud. There are two shifts: the Night-watch from midnight to noon, and the Day-team from noon to midnight. Whilst in the lab and, more importantly, out on deck, these have to wear armour: PPE (Personnel Protective Equipment) – a hard hat, hobnailed boots and some rather unflattering (generally oversized) overalls. The overalls are optional, but a sensible option at that; the job is a messy one, so unless you have an endless supply of clothes…. As the British Geological Survey (BGS) core team recover the mud to deck we have to wait – impatiently. How much have we recovered, and is it the right stuff? Even before the barrel is laid down we swarm expectantly around its end to get the first glimpse (and touch) of the treasure. The strength of the mud gives us so much information; we prod it, taste it…. Does it feel like silt, sand, clay; is it stiffened, reflecting the weight of former ice sheet bearing down on it? We recover everything from the core shoe, the core catcher; whatever sticks or falls out of the liner gets bagged, labelled, photographed and stored cool. But what is inside the liner is what we really want, it contains the story of the ice coming and going from the waters around these islands.

The liners are not easily released from the barrel; muscles are needed to get it out, and a tug-of-war ensues of scientists, BGS engineers, crew, random passers-by, anyone versus the barrel. But once the liner is out, it’s ours. The muds we desire are only useful if we know exactly where they are from, so labelling is everything. Every single core section has its own unique label, which will end up on its liner, caps, wrapping material, and the box it’s stored in. There are yellow caps for the tops and black for the base of each segment; which way is up matters! And that is only the beginning; there is no such thing as over-labelling, and that holds for cores sections, record sheets, scanned records, spreadsheets, photographs……

Lou: “The day shift consists of Steve, Zoe, Catriona, Kevin and me. Whilst Colm and Katrien spend the day planning where we will core next, we collect and process the cores. Generally our day starts at 11:20 with breakfast, which also happens to be lunch for the other crew members. Breakfast can be anything from a curry to fish and chips. Today’s option was Thai fish cakes, with noodles and sweet chilli sauce. Although having such a large meal first thing was rather odd to begin with, six weeks in it seems quite normal and a bowl of cereal would now disappoint. Shift begins with the midday handover meeting and our goodnights to the night team.

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Then work begins! We spend most of our shift either out on deck collecting and cutting the cores, or in the wet lab splitting, logging and packing the cores away with a constant dual stream of material either from the deep or from the MSCL cave. Frequently we split over 20 sections during our shift, and often it’s more than 25. Each section is 1 m long with each 1 m weighing between 10-12 kg, so after 12 hours of carrying, splitting, logging and packing it is a good workout. So the coring job may seem rather unglamorous and exceptionally mucky, and involves hard manual labour; it is also an exciting and rewarding part of the cruise. The sub-bottom profiles and bathymetry data provides a tantalising look at what might lie beneath, but it is only when the core is taken and the material viewed that you know whether or not we have captured the right material needed for the project, and whether there is something we can use for dating. Sometimes we are disappointed normally if we fail to guess correctly in the ‘guess-the-core-length’ sweepstake (Steve is slightly in the lead at the moment), but when a good core is opened, it changes the mood of everyone involved.

Our work still isn’t quite complete, cleaning and maintaining the lab ready for the night team, labelling, cropping and archiving all photographs, and Zoe dutifully scans all of the deck sheets. At midnight the night team relieves us and then we head either straight to bed or take a detour past the kitchen to get a post shift snack. A day shift favourite is Nutella (somewhere in the multi-verse other nutty spreads might exist) on toast. It is hungry work, coring!”

Margot: “the Nightwatch consists of Kasper, Riccardo, Jenny, myself and occasionally Richard (if he can drag himself away from the Geophysics, picking core sites and mostly chatting on deck). As we start our shift, we tend to find ourselves in the middle of a coring transect that has been planned before, so we of the night often start our shift on station, vibrocoring. We’ve discovered that Riccardo has a special talent for working hard but still staying clean, while Richard has the useful talent for removing almost any sediment from an unwilling core catcher. Kasper’s Danish (or Viking) muscles come in handy for removing the liner from the barrel, and Jenny has useful BGS contacts (which saves us, for instance, from running out of sample bags). I myself have developed the modest knack of writing upside down, for liner labelling purposes.

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Splitting and description has to wait until we receive cores from Elke and the core scanner cave, and she works 6AM to 6PM. The early part of the shift can be quite calm, if the core stations we have picked are far apart. Quite often nature festoons such a quiet early part of the shift with an amazing sunrise. The pace picks up dramatically as the cores start to emerge from the MSCL cave. It can get a bit hectic if we’re busily splitting and describing, interrupted by receiving new cores from the seabed. Core sections everywhere! But the splitting is exciting, as we get to see the whole sedimentary sequence for the first time. Do we have the ideal core, which consists of a subglacial till at the bottom, conformably overlain by marine sediments deposited after the ice retreated? Are there perhaps some nice shells in it for radiocarbon dating? When we see something we could use for 14C dating, we take it out. As we are coring, we have a competition running: guess the core length. It is very tight at the moment; Riccardo is in the lead, closely followed by Jenny, and Richard is trailing miles behind, but it all can still change, even with only two days to go. Eventually noon arrives, when we hand over to the day team, and then plonk down tiredly for lunch, which, for us, is more like late supper. After lunch and a cup of tea it’s bedtime! And then at around 11PM (ish) we get up again, and the sequence repeats.”

Treasure.....

Treasure…..

As we both write this, the 212th core has been recovered from the large moraine in outer Galway Bay. There is some 6 tonnes of mostly mud in our refrigerated container, and we have picked more than 100 shells for dating. But we know exactly where every kilo came from, what it looks like, and which ones we want to target for further research. When we get back on land, we can hit the ground running…..

Photography mostly by Alex Ingle, except where it isn’t….

Cruise 1 Leg 2: Transect completions coming thick and fast…..

By Richard Chiverrell

The leaving of Killybegs

The leaving of Killybegs

The Britice-Chrono Cruise through the Celtic, Irish and Malin Seas, and onwards around Ireland takes, in order, the Transects T4 (Irish Sea West), T3 (Irish Sea East), T7 (Malin Sea – Barra fan), T6 (Donegal) and T5 (Galway – Porcupine Bank). Leg 1 ran from Friday 18th July to Monday 4th August culminating with three cores as part of the Malin Sea transect, before our efforts in Donegal Bay were curtailed by rising seas and inclement weather. The port stop in Killibegs in northwest Ireland was a welcome break and chance to recharge batteries. It was also change time in terms of the Science Crew, with James Scourse, Sara Benetti, Fabio Sacchetti and Dan Praeg taking leave of the ship. Joining in Killybegs were Stephen Livingstone and Kevin Schiele, and Jenny Gales switched from BGS crew to the Science team for the second leg. Alex Ingle joined our throng as Film-maker. It was all change for the BGS core team, as we bade farewell to Davie, Alan, Keith, Mike and Joe, and welcomed (Day team) Iain (Rab) Pheasant, Apostolos Tsilligianis and Claire (taciturn) Mellett (Night team) David Wallis, Garry McGowan and Connor Richardson. Somehow I failed to leave the ship in Killybegs, either a desire to runaway to sea or perhaps oversleeping.

T6 Donegal Bay: the weather and seas relented for our time in and departure from Killybegs. we sailed in not the glorious sunshine that greeted our arrival and days sampling the shops and tea-rooms of this pretty fishing /industrial port in northwest Ireland. Our departure route was a sprint west, before a crisscross survey along a pronounced inner moraine from which seven cores were identified and sampled along and either side of this moraine complex. A further 13 were picked and recovered from an ~80 mile breakneck transect to the shelf break moraines fronting Donegal Bay. All in we were pretty pleased, another transect in the bag, a total of 20 vibrocores, just leaving the high risk more exposed locations: Malin Sea and Galway Bay – Porcupine Bank. Highlights included excellent thick sequences of laminated glacimarine muds, with occasional drop-stones and shells, some high priority targets for radiocarbon dating across the sea floor moraines preserved in Donegal Bay. In particular the blitzkrieg coring marathon 20 vibrocores in 27 hours to gently ease the 2nd leg BGS core team into the Britice-Chrono / RRS James Cook way of life, they loved every minute of it…..

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T7 Malin Sea – Barra Fan: it is amazing what can happen while you sleep; go to bed mid afternoon on the 6th Aug, when you wake midnight 7th Aug it is the start of the survey 100 miles further north in the Malin Sea (T6 sampling complete). The dynamism of a 24 hour work programme and day/night teamwork keeps you on your toes. The morning meetings chaired by the Captain (John Leask) focused on all manner of boat matters from plumbing to safety and our dynamic science plan. Featuring heavily as we approached the Malin Sea survey was the approaching remnants of Tropical Storm Bertha, though not actually to affect us that much, it reminded us how fickle weather and sea state can be, and how subject to conditions our programme could be before we would go alongside in Southampton on the 25th August. All in the Malin Sea T7 research saw us complete 40 cores, including 3 piston cores, and what felt like thousands of miles of geophysical survey. The transect saw heroic maintenance actions by the BGS team, repairing the electronics that drive the hammer system and a retraction winch cable (replaced in the 30 mins between core stations). By the end of T7 our tally of cores stood at 154, with >75 hours of hammering on the sea floor, devouring core catchers and our stocks of core tubes, and putting a heavy workload on our trusty vibrocorer. Hammering through diamict stiffened beneath the pressure of ice 24-26,000 years ago and smashing into the occasional lump of rafted bedrock, all contribute to a less than easy life. Highlights included thick sequences with glacimarine muds and possible diamicts at or near the continental shelf break, thick (>7m) piston core profiles from the deeper ocean and continental shelf slopes (>1500m of water) and further excellent cores in the outer sector of the Sea of the Hebrides, selected as we had to shelter from some choppy waters. A very satisfied team could take leave of the Malin Sea for pastures new……

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Selected photographs by Alex Ingle

An ugly ducking emerges from the ashes……

A blog from the early hours of the morning on the RRS James Cook

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Midnight, not a creature was sleeping and it was all noisy all around the ship…. The handover for the Science Team juddered (dynamic positioning in full flow) into view as day-watch passed the baton on to night-watch, Principal Science Officer or PSO (Colm Ó Cofaigh) having formulated and briefed us on the plan (Plan A)for the next 24-36 hours. It can be tiring as the science lead on the Cruise, and so retiring for a well earned rest at the end of shift is a much encouraged seldom realised dream…..

We progressed rapidly to the fourth of nine vibrocore locations on the overnight plan (Plan A) about 10 miles from the break in slope at the edge of the continental shelf in the Malin Sea. BGS night team lowered the vibrocorer to the seabed and prepared to commence operations. There was no response from the seabed, something was clearly amiss. After a quick abort and return to the deck, the BGS team set about analysing the problem, sparks flew; clearly the fault lay with the electronics. After checking timescales for assessment and repair, and that this could be undertaken under steam, we woke PSO about 2.30 am, no doubt fully rested after 1.5 hours sleep to formulate an alternate plan…

Plan B quickly emerged and comprised several components, first hopefully fixing the vibrocorer, and second the Science team switching focus to other activities. We commenced a programme of sub-bottom profiler and multibeam survey heading northwest ~35 miles to possible piston core locations, and there we completed a 25 mile survey from >1600m of water across the shelf break into 300m of water, our challenge was to find some piston corer targets with possible glacimarine sediments. Meanwhile an at times nine person strong team of BGS team and RRS James Cook crew worked through the early hours to isolate the problem and hopefully to fix it (Plan C). With the JC106 Cruise schedule including further work out in the Malin Sea and the entire work programme for T5 Galway Bay including work on Porcupine Bank we could little afford a port call (Plan D) in the Western Highlands of Scotland. We also very much needed the vibrocorer which had delivered ~130 sediment profile from very tough glacigenic muds. If it had failed completely, an outside chance, we would be limited to geophysical survey and piston coring on Porcupine Bank (a much dreaded Plan E) and some rethinking for Cruise 2…..

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Dawn came and went, as we waited on smoke signals from the back deck (well more accurately the absence of smoke signals….) the good news arrived at breakfast things were looking less terminal. The fault had been isolated (a very well hidden cable uncoupled and affected by sea water) and promptly repaired, all that remains was reassembly and some testing first on deck and then in the water. BGS team and the deck crew get some very well deserved and earned rest. The wet vibrocore test then lay ahead, with 2 piston cores in 1575 and 1200m of water for day watch who took charge in the midday clouds…. Somewhere the sun set, the moon rose, apparently a supermoon – not bad at all, and we awoke to news of two successful >7m length recoveries for the piston cores in deep waters and on the continental shelf slope, plus critically a deepish water deployment of the vibrocorer on the shelf break ~500m of water. Success….. >3m of mud recovered, 136 vibrocores collected and going strong…..

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A relieved, tired and happy PSO could take leave of the watch, with an invigorated and expanded Plan C trending forwards into the foreseeable feature, vibrocore four of nine (3.92m), five of nine (0.4m), six of nine approaches…..

We are on schedule as always, the Plan is strong, the Plan is all-knowing, the Plan are legion, the Plan are many…..

Kasper's moon....

Selected photographs by Alex Ingle

A room without a view……

By Elke Hanenkamp (MSCL Operator)

Enter my lair

Enter my lair

Six o’clock in the morning on board the RRS James Cook somewhere on the edge of Malin Sea in 1500m of water, and my shift as the MSCL operator starts right now. The dayshift (midday to midnight) is still fast asleep and the nightshift (midnight to midday) scientists are eagerly (or maybe more fatalistically) awaiting my arrival. The beginning of my shift marks the start for them that cores can finally be split and described soon (meaning more work for them), therefore I have been jokingly nicknamed “the harbinger of cores”.

My role during this expedition is to collect physical properties data (density, porosity etc) from the vibro and piston cores before they are split on board. I am operating a Geotek Multi-Sensor Core Logger (MSCL) in a containerised lab (also known as “the container cave”, I am in there all the time holed up with the cores). So the obvious question is – what is happening behind the closed door of the container? After the cores come aboard, they are cut into sections and labelled, and then stored for at least 6 hours inside the container to equilibrate to ambient temperature. Only after this period, the cores will be measured on the MSCL, because some of the sensors are temperature sensitive. It is not possible to prop the door open during the measurements, fluctuations in temperature would influence the data. That’s why I am holed up in the container most of the time, every so often delivering already measured cores to the scientists for splitting or taking newly labelled cores into the container.

The Multi Sensor Core Logger is a quite versatile core measurement system, equipped with four sensors – Gamma Density, P-Wave Velocity, Non-Contact Resistivity and Magnetic Susceptibility. While the core is pushed past the stationary sensors, it is scanned, and data from all four sensors is collected at once when the core pauses at a measurement point (in this case every 2 cm). Sequential core sections are loaded on to the logger, this way a complete core can be logged in a continuous process while the data is displayed graphically in real time on the computer. Typically, with measurements being done every 2 cm, a 1 m section can be logged within 15 min, but overall measurement time for one whole core depends on the amount and length of each individual section the core is cut into earlier. The shortest core section we had so far measured only 21 cm. The amount of cores sections measured each day highly varies, but a couple of days ago, 45 sections were measured on the MSCL within my 12 hour-shift, with a total length of a little bit over 41 m (a new record).

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The MSCL gives us a non-destructive way of analysing cores before they are split and sampled. The measurements can help to characterise the physical nature of the individual cores, e.g. lithology, density, porosity, and will be used in combination with core descriptions and various geochronological data to better understand the timing of ice sheet recession. The high-resolution dataset from the MSCL should also allow us to make correlations between individual core sites in the Celtic, Irish and Malin Seas fringing the North Atlantic.

A view of the world

A view of the world